For those familiar with the novels by George R.R. Martin that serve as the basis for the series, the third season was planned to cover only the first half of the third book, "A Storm of Swords." Now fans will be able to see at least the rest of the events of that book dramatized on TV.

After the fourth season, however, things will get trickier. When the books were published, Martin made the decision to divide the fourth and fifth books, "A Feast for Crows" and "A Dance With Dragons," by characters, with half of the storylines in one book and the other half in the other book (though there is some blending of stories in the fifth volume).

When those books make it to TV, elements of both books will need to be blended to continue the ongoing narrative of all the characters.

And then, of course, there's the question of what happens after that. Martin is still hard at work on the series' sixth book, with one more to go after that. Still no word on when the book will be finished, or how much time he will need to write the final book.

The show's executive producers, David Benioff and D.B. Weiss, told HitFix that they visited Martin at his home in New Mexico in February to get information on where the series was headed in the final two books.

In Westeros, winter may be coming, but in the real world, deadlines are coming. And they're much scarier.